Like I said, it's current battle scale does not make it an MMO. But it's a closed gameplay beta afterall, it doesn't need to be feature complete at this point. The systems are there and the future plans are there to change that however.
There is no browser. Singe point of entry means that everyone joins the game through the same point on the same server; for example - at present there are approximately 2400 people connected to the world. The server then organises players into instances of the various maps for battles when people choose to enter combat. At present this is limited to 15 v 15 with a mix of German and Russian vehicles. Future additions will add 30 vs 30 battles along with nation vs nation, the inclusion of 4 more nations and infantry to battles.
Currently the persistence is limited to player 'characters', in future it will very likely (it's has been strongly hinted but not confirmed yet) include a persistent meta game around the progress of the 'war'. That's your persistent world.
At the end of the day, unless the developers fail to implement their planned features for whatever reason, the final product will be an MMO based around players driving tanks. Why shouldn't they market it as such pre-release?